I have never had much luck with plecos actually doing a good job eating algea. My current one i think went on strike. He likes his vegetables and the cories food as far as algea not so much. Snails seem to do the best job atleast glass wise. Shrimp do the best job on plants and substrate. So some shrimp and a couple snails would probably be the best plan. I have always had a pleco since they are neat but as with everything else they need fed too.
I have some Siamese algae eaters in a 55. They like to clean my Marimo moss ball and are always schooling. They are very interesting. But you have to find a real one and not get scammed for a flying fox which has black fins not clear fins